Histamine H3 receptor is a G-protein coupled receptor (GPCR) and one out of the four receptors of Histamine family. Histamine H3 receptor is identified in 1983 and its cloning and characterization were done in 1999. Histamine H3 receptor is expressed to a larger extent in central nervous system and lesser extent in the peripheral nervous system.
Literature evidence suggests that Histamine H3 receptor ligands can be used in treatment of cognitive disorders (British Journal of Pharmacology, 2008, 154(6), 1166-1181), dementia (Drug News Perspective, 2010, 23(2), 99-103), attention deficit hyperactivity disorder, obesity (Indian Journal of Pharmacology, 2001, 33, 17-28), schizophrenia (Biochemical Pharmacology, 2007, 73(8), 1215-1224) and pain (Journal of Pharmacology and Experimental Therapeutics, 2011, 336(1), 30-37).
Patent publications WO 2007/137955, US 2009/0170869, US 2010/0029608, US 2010/0048580, WO 2009/100120, WO 2009/121812 and WO 2009/135842 disclosed series of compounds as ligands at Histamine H3 receptors. While some Histamine H3 receptor ligands have been disclosed, no compound till date is launched in market in this area of research, and there still exists a need and scope to discover new drugs with novel chemical structures for treatment of disorders affected by Histamine H3 receptors.